import type InstantSearch from '../lib/InstantSearch';
import type { UiState } from './ui-state';
import type { AtLeastOne } from './utils';
export type MiddlewareDefinition<TUiState extends UiState = UiState> = {
    /**
     * string to identify the middleware
     */
    $$type: string;
    /**
     * Change handler called on every UiState change
     */
    onStateChange: (options: {
        uiState: TUiState;
    }) => void;
    /**
     * Called when the middleware is added to InstantSearch
     */
    subscribe: () => void;
    /**
     * Called when InstantSearch is started
     */
    started: () => void;
    /**
     * Called when the middleware is removed from InstantSearch
     */
    unsubscribe: () => void;
};
export type MiddlewareOptions = {
    instantSearchInstance: InstantSearch;
};
export type InternalMiddleware<TUiState extends UiState = UiState> = (options: MiddlewareOptions) => MiddlewareDefinition<TUiState>;
export type Middleware<TUiState extends UiState = UiState> = (options: MiddlewareOptions) => AtLeastOne<MiddlewareDefinition<TUiState>>;